Originally Posted by
Retro Grouch
In real life you might not need as much slack take up capacity as the calculations suggest.
Do you use all of your freewheel gears in combination with your granny chainring? I certainly don't. The only time that I use my granny is on steep hills and only in combination with my biggest couple of rear cogs. If I never shift into the 30/14 combination, I don't need enough slack take up to handle that combination.
+1. As long as the chain is made long enough to shift safely into big-big, you can sacrifice the ability to use small-small with no problems. All that happens if you forget is that the chain goes slack and it's a bit noisy. As RG notes, there is no need for small-small as the same gear is available elsewhere.